siRNA targeting the IRF2 transcription factor inhibits leukaemic cell growth

The nuclear factor of activated T cells (NFAT) family of transcription factors is expressed in a wide range of cell types and regulates genes involved in cell cycle, differentiation, and apoptosis. NFAT proteins share two well-conserved regions, the regulatory domain and the DNA binding domain. The N-and C-terminal ends are transactivation sites and show less sequence similarity, whereas their molecular functions remain poorly understood. Here, we identified a transcriptional repressor, interferon regulatory factor 2 binding protein 2 (IRF-2BP2), which specifically interacts with the C-terminal domain of NFAT1 among the NFAT family members. IRF-2BP2 was described as a corepressor by inhibiting both enhancer-activated and basal transcription. Gene reporter assays demonstrated that IRF-2BP2 represses the NFAT1-dependent transactivation of NFAT-responsive promoters. The ectopic expression of IRF-2BP2 in CD4 T cells resulted in decreased interleukin-2 (IL-2) and IL-4 production, supporting a repressive function of IRF-2BP2 for NFAT target genes. Furthermore, NFAT1 and IRF-2BP2 colocalized in the nucleus in activated cells, and the mutation of a newly identified nuclear localization signal in the IRF-2BP2 rendered it cytoplasmic, abolishing its repressive effect on NFAT1 activity. Collectively, our data demonstrate that IRF-2BP2 is a negative regulator of the NFAT1 transcription factor and suggest that NFAT1 repression occurs at the transcriptional level.The regulation of eukaryotic gene expression is a coordinated action of basal transcriptional machinery, chromatin remodeling factors, and transcriptional factors that bind specific elements in promoters and enhancers; these components form a complex network of protein-protein interactions for the proper regulation of mRNA transcription (37). Nuclear factor of activated T cells (NFAT) transcriptional factor, first identified as an inducible nuclear factor that binds the interleukin-2 (IL-2) promoter in activated T cells (57), plays an important role in the control of gene expression in a wide range of cell types and tissues (42, 65). The NFAT family consists of four members that are regulated by calcium and the calcineurin signaling pathway, known as NFAT1 (also called NFATp or NFATc2), NFAT2 (NFATc or NFATc1), NFAT3 (NFATc4), and NFAT4 (NFATx or NFATc3) (42, 52). A fifth member, NFAT5 (TonEBP or OREBP), is regulated by hyperosmotic stress (40, 45).All NFAT members share a highly conserved DNA binding domain (DBD) that is structurally related to the DBD of the Rel family of transcriptional factors and confers a common DNA-binding specificity to all NFAT proteins (52). The calcium-regulated members, NFAT1 to NFAT4, have a second conserved domain, the NFAT homology region (NHR). This region contains several serines that are phosphorylated when these proteins are in their inactive cytoplasmic forms, and it also contains the docking site for calcineurin and NFAT kinases (42, 52). The high degree of amino acid sequence conservation of the DBD and NHR among the different N...

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“…Waf1 tumor suppressor effects (11). The IRF-2BP2 knockdown data from U2OS cells seem to support this model (35).…”

Section: Discussionmentioning

confidence: 90%

Interferon Regulatory Factor 2 Binding Protein 2 Is a New NFAT1 Partner and Represses Its Transcriptional Activity

Carneiro

Ramalho-Oliveira

Mognol

et al. 2011

Molecular and Cellular Biology

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“…In diverse types of cancers, the expression of IRF-2 was found to positively associate with the malignant phenotype and be critical for the tumorigenicity of cancer cells [20,24,26]. Previous studies indicated that IRF-2 exerts it oncogenic activity in ESCC by affecting expression of certain genes involved in cell proliferation and apoptosis [25,26].…”

Section: Discussionmentioning

confidence: 97%

“…Recently, more and more evidence uncovered the pivotal role of IRF-2 in tumor progression [18,19]. By suppressing the function of p21, IRF-2 promoted cell growth in leukemogenesis, and knockdown of IRF-2 blocked leukemia cell growth [20,21]. Elevated expression of IRF-2 was found in breast cancer, which was positively correlated to the tumor stage [22][23][24].…”

Section: Introductionmentioning

confidence: 98%

IRF-2 is over-expressed in pancreatic cancer and promotes the growth of pancreatic cancer cells

et al. 2011

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Pancreatic cancer is one of the most malignant diseases in the world. Interferon regulator factor 2 (IRF-2), an interferon regulatory factor, has been known to act as an oncogene in distinct types of cancer. In this study, we found that the expression of IRF-2 was up-regulated in primary pancreatic cancer samples and associated with tumor size, differentiation, tumor-node-metastasis stage, and survival of the patients. In pancreatic cancer cells, knockdown on the expression of IRF-2 inhibited cell growth in the liquid culture and on the soft agar. Mechanistically, IRF-2 modulated the growth of pancreatic cancer cells through regulating proliferation and apoptosis effectors, such as cyclin D1 and BAX. Collectively, these results suggest that IRF-2 plays an important role in the tumorigenesis of pancreatic cancer and down-regulation of IRF-2 would be a new treatment target for pancreatic cancer.

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“…Also, IRF2 knock-down associated growth inhibition and induction of differentiation in a leukemia cell line further emphasizes the role of IRF2 deregulation in leukemogenesis. 37 Moreover, the receptor tyrosine kinase KIT, important for normal hematopoiesis, 38 was validated as a target of several NPM1 mut -associated miRNAs. KIT is crucial for maintaining HSC self-renewal and quiescence and was shown to be down-regulated in IRF2 deficient cells.…”

Section: Ccnd1mentioning

confidence: 99%

Integrative nucleophosmin mutation-associated microRNA and gene expression pattern analysis identifies novel microRNA - target gene interactions in acute myeloid leukemia

Russ¹,

Sander²,

Lück³

et al. 2011

Haematologica

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The online version of this article has a Supplementary Appendix. BackgroundMicroRNAs are regulators of gene expression, which act mainly by decreasing mRNA levels of their multiple targets. Deregulated microRNA expression has been shown for acute myeloid leukemia, a disease also characterized by altered gene expression associated with distinct genomic aberrations such as nucleophosmin (NPM1) mutations. To shed further light on the role of deregulated microRNA and gene expression in cytogenetically normal acute myeloid leukemia with NPM1 mutation we performed an integrative analysis of microRNA and mRNA expression data sets. Design and MethodsBoth microRNA and gene expression profiles were investigated in samples from a cohort of adult cytogenetically normal acute myeloid leukemia patients (n=43; median age 46 years, range 23-60 years) with known NPM1 mutation status (n=23 mutated, n=20 wild-type) and the data were integratively analyzed. Putative microRNA-mRNA interactions were validated by quantitative reverse transcriptase polymerase chain reaction, western blotting and luciferase reporter assays. For selected microRNAs, sensitivity of microRNA-overexpressing cells to cytarabine treatment was tested by FACS viability and cell proliferation assays. ResultsOur integrative approach of analyzing both microRNA-and gene expression profiles in parallel resulted in a refined list of putative target genes affected by NPM1 mutation-associated microRNA deregulation. Of 177 putative microRNA -target mRNA interactions we identified and validated 77 novel candidates with known or potential involvement in leukemogenesis, such as IRF2-miR-20a, . Furthermore, our data showed that deregulated expression of tumor suppressor microRNAs, such as miR-29a and miR-30c, might contribute to sensitivity to cytarabine, which is observed in NPM1 mutated acute myeloid leukemia. ConclusionsOverall, our observations highlight that integrative data analysis approaches can improve insights into leukemia biology, and lead to the identification of novel microRNA -target gene interactions of potential relevance for acute myeloid leukemia treatment.Key words: microRNA, miRNA, gene expression profiling, GEP, acute myeloid leukemia, AML, NPM1 mutation.Citation: Russ AC, Sander S, Lück SC, Lang KM, Bauer M, Rücker FG, Kestler HA, Schlenk RF, Döhner H, Holzmann K, Döhner K, and Bullinger L. Integrative nucleophosmin mutation-associated microRNA and gene expression pattern analysis identifies novel microRNA -target gene interactions in acute myeloid leukemia.

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siRNA targeting the IRF2 transcription factor inhibits leukaemic cell growth

Cited by 16 publications

References 13 publications

Interferon Regulatory Factor 2 Binding Protein 2 Is a New NFAT1 Partner and Represses Its Transcriptional Activity

Interferon Regulatory Factor 2 Binding Protein 2 Is a New NFAT1 Partner and Represses Its Transcriptional Activity

IRF-2 is over-expressed in pancreatic cancer and promotes the growth of pancreatic cancer cells

Integrative nucleophosmin mutation-associated microRNA and gene expression pattern analysis identifies novel microRNA - target gene interactions in acute myeloid leukemia

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